In order to redefine the default media query ranges in _settings.scss, you need to import "foundation/functions" so that the function 'lower-bound' is defined. The current comment implies you only need it for the function 'rem-calc'.
// This is the default html and body font-size for the base rem value.
// $rem-base: 16px;
-// Uncomment to use rem-calc() in your settings
+// Uncomment to use rem-calc() or lower-bound() in your settings
@import "foundation/functions";
// $experimental: true;